Create a Read-Only DB Role for Agents Agent Skill

Provision a hardened SELECT-only Postgres role so AI agents can safely read a production database.

Context cost
1.4k tokensestimated from the bundle, loaded when it triggers
Bundle
1 file · 5.4 kBtext throughout, nothing executable
Licence
not declarednone named by its author
Last change
—no release on file
Servers it uses
Noneruns standalone

What it does

Provision a hardened SELECT-only Postgres role so AI agents can safely read a production database. Works on Supabase and any Postgres. Use when the user wants agents to query prod data, says "read-only role", "safe prod DB access for agents", or is tired of running SQL by hand for agents. Differentiator: this skill CREATES the role and wiring; day-to-day querying belongs in a project-local skill.

What this skill changes about the agent has not been set out here as a list. Its SKILL.md, shown below, says it in the author’s own words.

databasepostgres
Filed under

Databases

The skill itself

A skill is instructions the model reads, so you can see what you are getting: below is the start of its SKILL.md. The front matter loads with every session, the body loads when the skill triggers, and the whole file comes with the install.

SKILL.md5.4 kB · preview
--- name: create-readonly-db-role ---
6# Create a Read-Only DB Role for Agents
7
8Battle-tested pattern (DeepAPI ADR 0093). A SELECT-only role kills catastrophic writes at the permission level. Residual risks (data leaks, heavy queries) are handled by a denylist and timeouts. Agents stop being blind on prod; the human stops being the SQL bottleneck.
9
10## The pattern — 3 layers
11
121. **Hard wall — grants.** The role gets SELECT and nothing else. Writes are impossible, not just discouraged.
132. **Denylist, not allowlist.** Grant SELECT on ALL current + future tables in public (via default privileges), then revoke the crown jewels (API keys, webhook payloads, secrets). Never grant the auth schema. Future tables are auto-readable by design; new sensitive tables need a manual revoke.
143. **Soft guardrails.** default_transaction_read_only = on plus statement_timeout = '10s'.
15
16**RLS trap:** if prod tables have Row Level Security and no policy mentions the new role, every SELECT returns 0 rows. Fix with alter role ... bypassrls — safe, because bypass only skips row filtering; the SELECT-only grants and denylist still apply.
17
18## Workflow
19
201. **State-check.** select rolname from pg_roles where rolname = 'agents_readonly'; — if it exists, you are updating, not creating.
212. **Pick the denylist with the human.** Ask which tables hold secrets or PII that agents must never see (API keys, webhook events, auth/user tables).
223. **Write the SQL to a repo file first** (e.g. docs/database/create-agents-readonly-role.sql) with comments: what / why / how to apply / how to verify / how to revert. Never hand SQL only in chat.
234. **The human applies it** — agents never run DDL on prod. Supabase: paste the whole file into the SQL editor, then DELETE the query from editor history (it contains the password). Store the password in a password manager.
245. **Wire the connection string** as a local env var in ~/.zshrc (never committed), e.g. MYPROJ_READONLY_DB_URL. Supabase session pooler: username is agents_readonly.<project-ref>, port 5432. psql comes from Homebrew libpq if missing.
This is a preview of SKILL.md. Download or install the skill to get the whole thing.
In the file
SKILL.md811 words
Files1
Licencenot declared
Why you can read it

Nothing in a skill executes. The client loads the text and the model follows it, so a skill can be audited the way a runbook is — by reading it.

What it costs in context

Skills are not billed by the call. They are paid for in context: every token the instructions occupy is a token your code, your diff and your conversation cannot use. Here is what this one takes and when it takes it.

≈110
always loaded
The name and description, so the model knows the skill exists and when to reach for it.
1,240
on trigger
The instruction body, read only when the skill fires.
0.68%
of a 200k window
Ten skills this size would take about 7% of the window before you open a file.
050k100k150k200k context window

1.4k tokens, estimated from the bundle at four bytes to the token, held for the rest of the session once it triggers. Middling. Fine to keep on in a project where you use it weekly, worth unloading in one where you never do.

Servers bill, skills cost

A server charges by the month. A skill charges once per session, in context, and then keeps charging it for as long as the session lives.

Before and after

The same question, put to the same model twice: once as it comes, and once with these instructions loaded.

No worked example has been published for this skill yet.

The procedure it runs

The procedure has not been set out here step by step. It is in the body of its SKILL.md: the start of it is shown above, and the whole file comes with the install.

Prose, not code

These steps are written for a model to follow, not executed by a runtime. It can still be told to skip one, and it will say so when it does.

Servers it uses

None. This skill calls no MCP servers at all.

Everything it needs is in the instructions, so it works in a project with nothing connected — the model reads the file and changes how it works with what it can already reach.

Its SKILL.md does not declare which tools it asks the agent for, so what it touches is whatever the instructions themselves ask for — read them before you install it.

What it asks for
Writes filesnot declared
Network accessnot declared

This SKILL.md carries no allowed-tools line, so neither is declared. A skill grants no permissions of its own — it can only ask for tools your client already has.

What it will not do

Every skill is narrow, and the useful ones say where they stop. These are the jobs this one is the wrong tool for.

What this skill is not for has not been published here. Nothing is implied by that: it is a section the author has not filled in.

What is in the bundle

1 file, 5.4 kB on disk. A bundle is text throughout: the instructions the model reads, plus the templates it fills in.

  • SKILL.md5.4 kB
What is not in it

No dependencies and nothing executable: a skill is text the agent reads, so the bundle is 1 file you can review in full before installing.

Install

Installing copies the bundle into your project. Nothing runs at install time — the files sit on disk until the model reads them.

# Create a Read-Only DB Role for Agents · 1.4k tokens when loaded · macOS, Linux mkdir -p .claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/create-a-read-only-db-role-for-agents/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/create-a-read-only-db-role-for-agents" ] && { [ ! -e .claude/skills/create-a-read-only-db-role-for-agents ] || { mv .claude/skills/create-a-read-only-db-role-for-agents "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/create-a-read-only-db-role-for-agents" .claude/skills/ && echo "Installed .claude/skills/create-a-read-only-db-role-for-agents"
On Windows, or any OS with Node 20+
npx mcprush@latest skill add karanmrn/create-a-read-only-db-role-for-agents

Windows PowerShell says 'running scripts is disabled on this system'? Run Set-ExecutionPolicy -Scope CurrentUser RemoteSigned once, or type npx.cmd instead of npx (codex.cmd, gemini.cmd, grok.cmd likewise). PowerShell 7 needs neither. Writes to .claude/skills/create-a-read-only-db-role-for-agents/ in the current project. For every project instead, run mkdir -p ~/.claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/create-a-read-only-db-role-for-agents/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/create-a-read-only-db-role-for-agents" ] && { [ ! -e ~/.claude/skills/create-a-read-only-db-role-for-agents ] || { mv ~/.claude/skills/create-a-read-only-db-role-for-agents "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/create-a-read-only-db-role-for-agents" ~/.claude/skills/ && echo "Installed ~/.claude/skills/create-a-read-only-db-role-for-agents" (macOS, Linux) — or add --global to the npx line. The curl line replaces .claude/skills/create-a-read-only-db-role-for-agents/ only after the download succeeds, so files left there by another skill of the same name, or by an older release, do not mix in. A copy already there is moved aside, not deleted, and the line prints where. It appears as create-readonly-db-role in Gemini CLI, Codex, Copilot and Grok (its own name); Claude Code lists it by the folder name, create-a-read-only-db-role-for-agents.

Which clients pick it up on their own

A skill is a folder of text. Most of these read a skills folder and pick it up without being told; the rest take the same folder another way — an upload in the app, a parameter on an API call — and then choose it by its description just the same.

Claude Code.claude/skills/
Claude DesktopCustomize › Skills
ChatGPTSkills › Create › Upload
Cursor.cursor/skills/
VS Code.github/skills/
Codex CLI.agents/skills/
Gemini CLI.gemini/skills/
Grok Build.grok/skills/
Microsoft CopilotSkills › Upload a skill
PerplexityComputer › Skills › Upload a skill
DeepSeek Harness.dsh/skills/
Zed.agents/skills/
Devin Desktop.devin/skills/
Windsurf (legacy).windsurf/skills/
OpenAI Agents SDKInstructions or sandbox Skills
HTTP / APIa request parameter
This release
Versionnot versioned
Publishedno release date on file
PriceFree
Referencekaranmrn/create-a-read-only-db-role-for-agents

Versions

Its author publishes no version number, so there is nothing here to pin to: what you install is the folder as it stands today. Instructions change more often than APIs do — a skill can be rewritten entirely without anything it depends on moving.

Pinning

Nothing to pin to: this skill carries no version number of its own. What you install is what the folder holds on the day you install it.

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